This invention relates generally to frequency selecting arrangements and more particularly to a multiposition manually operable channel selector switching arrangement for a transceiver which provides the desired transmitter output frequency in the transmit mode of operation and the appropriate local oscillator injection frequency in the receive mode of operation.
Arrangements for selecting operating frequencies for radio frequency transmitters and receivers are well known and vary in sophistication from a variable reactance in a tuned circuit to so-called frequency synthesizers. Such synthesizers may derive frequency steps typically decadic from a crystal stabilized frequency standard by harmonic generation and frequency division and may also include a variable frequency source to fill in between the frequency steps thereby providing a wide range of frequencies using relatively few crystals or other basic frequency sources. Another type of frequency synthesizer employs a reference frequency source and a controllable oscillator with the controllable oscillator output and the reference frequency source being compared by a feedback arrangement and the results of that comparison used to modify the controllable oscillator to provide the desired output frequency. Multiples or aliquot portions of the controllable oscillator output may be compared to the reference frequency as needed to provide the desired output frequency range. In a multichannel transceiver, frequency generation of this phase lock variety is known, however, when a large number of channels are to be provided along with several selectable operating modes, the switching problems become increasingly complex from the manufacturer's and/or user's point of view.